If you both reside at the same address you should have no problem getting added to the same plan as your boyfriend. While this could possibly raise the rate that he is currently paying, it will likely come out as cheaper on the whole.
The claim payout for the total loss will only go to the lienholder or owner and not a third party. Your boyfriend will need to somehow sign the check or the vehicle over to you so you can remedy the situation.
You would both need to be on the policy since he will be driving the car and you will own it. If you will not be driving the car, he can get the policy in his name but you will need to be listed as an excluded driver, which means you are not covered to drive the car.